Future robots
will learn their moves from cockroaches, crabs and
centipedes

By Robert
Sanders, Public Affairs
Posted May 10, 2000

At San Diego's Sea World, Rodger Kram videotapes penguins
waddling across a force-measuring platform to rate the
energy efficiency of their distinctive gait. Meanwhile, at
Berkeley, Claire Farley tapes bright dots to the legs of
students and videotapes them running across a similar
platform to determine the relationship between muscle
stiffness and springy legs.

Across campus, Robert Full tests cockroaches, crabs and
centipedes to discover how springy legs provide stability,
while down the hall, Steven Lehman stretches rabbit muscle
fibers to find out how they work as brakes and springs as
well as motors.

Michael Dickinson tracks blowflies in a test chamber to
determine how feedback from their eyes affects the flight
muscles and ultimately allows spectacular maneuverability.
And Mimi Koehl builds foot-long models of lobster antennules
to learn how these crustacean noses pluck odor molecules
from the water swirling around them.

These half-dozen Berkeley professors in the Department of
Integrative Biology comprise the largest and most diverse
group in the country studying how animals -- including
humans -- move.

What has emerged from the comparative biomechanics group
and from their associates around the world are a set of
principles that apply to animal locomotion of all kinds,
whether it's running, swimming, flying or wriggling. As
Koehl has found, these principles even apply to movement not
associated with locomotion -- with sampling the environment,
capturing food or just trying to stay put in the face of
wind or water currents.

Last month, the Berkeley team summarized key findings
from more than a decade of research at Berkeley and
elsewhere in a review article titled "How animals move: an
integrative approach," published in the journal Science.

Such principles are not merely academic. Full, Koehl and
Dickinson, for example, regularly share information with
engineers eager to learn the secrets of animals' amazing
speed, control and mechanical stability so that they can
adapt the principles to the design of robots. Lehman has
found that his work on muscle fatigue is of interest to
ergonomics specialists trying to deal with an epidemic of
repetitive stress problems.

Kram, an assistant professor, recently hosted computer
animators from Pixar Animation Studios to give them tips on
creating more realistic animal movement for their next
blockbuster movie. Full consulted with Pixar earlier on "A
Bug's Life."

"In classic locomotion research, everyone focused on the
force pushing an animal forward. Power and efficiency became
central," said Dickinson. "That emphasis has really shifted,
because the way animals execute motion is very, very complex
and dynamic. Animals throw force out in all directions,
seemingly out of control and not optimized for moving in one
direction. We've found that these forces help produce
stability and maneuverability."

One of the key recent findings in the field of
biomechanics, Full added, is "that it's not how much power
animals can produce, but how they stabilize and control
themselves."

Full has demonstrated this with numerous creatures. He
has shown that these animals run by bouncing along like pogo
sticks with the same patterns seen in humans. The difference
lies in the squat stance, where splayed, springy legs are
superb in providing passive stability. This frees the brain
to deal with navigation rather than tedious,
instant-by-instant corrections at all the joints.

"The control is built into the structure, their sprawling
stance," he said. "It's a self-stabilizing system that can
simplify immensely how we think about animal motion, and
help in the design of robots no one has seen before."

A major strength of the group is collaboration. This
often emerges from weekly meetings where faculty, students
and postdocs assemble to hear about new work and, as the
seminar winds down, throw out silly ideas that often lead to
great insight.

Kram noted how one student mentored by Koehl and Full
used his findings on how humans move in reduced gravity --
he had suspended human volunteers from a harness while
running -- to predict how crabs move underwater. When the
student videotaped real crabs, she found the predictions to
be amazingly accurate. These data led to the design of
Ariel, the first legged amphibious robot.

Many of the principles discovered are now being co-opted
by engineers to design robots. Dickinson is working with
Berkeley engineer Ron Fearing to design a robotic fly, while
Full is collaborating with various robotics labs to create
robots that use principles employed by cockroaches, crabs
and even geckos.

"With the invention of artificial muscles and novel
techniques to manufacture flexible body parts," said Full,
"we are on the verge of a revolution in biologically
inspired robotics.

"Nature can now be a good teacher of engineers. But you
don't want to copy, you want to extract principles," he
said. "Nature has all kinds of screw-ups. Evolution is based
on the principle of just good enough, it's not perfect at
all. I think we can build robots today better than any one
organism. We can do that now."